As one can understand, the prior art is concerned with making medical tests available to the consumer at reasonable prices so that patients, nurses, as well as inexperienced individuals can monitor medical conditions. In particular, a widely used and familiar test concerns the measurement of glucose. The glucose test system is designed to be used by an individual, for example, a person who has diabetes, and is available over-the-counter. As one can ascertain, the glucose test market is enormous. Significant work has been done over many years by many large companies to improve the glucose test procedure and to reduce its cost and streamline the manufacturing techniques and test systems used.
In the glucose test system, a test strip is employed. The patient places a drop of blood on the test strip, the drop of blood having being obtained by conventional incision making or fingerstick devices, as are well known. The system then utilizes the test strip and essentially measures the glucose, by means of a glucose test and displays the results on a conventional meter.
The present apparatus employs optical detection to determine the hemoglobin content of a whole blood sample and uses a reagent that is free of cyanides, azides and carcinogens to enable the instrumented assessment of the hemoglobin content of whole blood. The reagent formulation is impregnated into a suitable mesh/membrane matrix that serves as an optical baseline for the optical measurement. The test method utilizes a common diffuse reflectance optical technique, operating on the test or reflecting surface of the membrane. The membrane surface is saturated with the red-colored hemoglobin and the system accurately measures the hemoglobin content of the whole blood sample and displays the results on a meter. A single drop of blood is applied to the test area of the test strip. The test well area is covered by the hydrophilic mesh. This mesh covering facilitates dispersion of the blood across the entire membrane upper surface. The uniform dispersion of the sample initially results in uniform infiltration of the membrane matrix. Uniform dispersion and infiltration results in uniform coloration of the membrane test surface. The lower surface receives the released hemoglobin and is discolored. The test sample blood is obtained from a fingerstick or other device. The test actually requires less than one drop of blood and is not compromised by additional sample volume. Excess sample is captured and restrained by the mesh and the membrane matrix. The membrane pores are blocked by non-hemolysed red cells and hemolysed cell debris. The mesh and membrane infiltration volume is therefore limited and the test surface, as a result, is not wetted but rather just colored. Wetting creates undesirable specular reflectance.
Additional sample volume is easily dealt with by the mesh membrane matrix. The test results are not compromised by the excess sample volume. Low volume, however, can cause errors in the system. The system, therefore, has a low volume test within the software. The hemoglobin content is rapidly determined and displayed after only 5 to 29 seconds.
The meter performance has been specifically and favorably compared to existing methods, including devices supplied by other companies. The test can be performed at the point of care, in a physician's office lab, in a hospital or any other environment where a patient is at risk and whose hemoglobin content must be known to facilitate medical diagnosis and treatment. The meter is portable and battery-powered, utilizing a common readily available coin type battery. As will be explained, the test strips employed are durable with a good shelf life. The twenty five test strip container has a built-in dessicator to help preserve the unused test strips in the container during use. Each container will be labeled and marked with a lot number, date of manufacture and a characteristic lot-specific code number. As will be explained, the system is user friendly and requires only a small drop of blood for test purposes. The sample target spot is highlighted by test strip graphics and the surrounding area of the meter is flat allowing easy access, reducing the potential for spillage or contamination. The test strip entry surround, including the sample introduction area, is easily removed for cleaning or replacement as required. The entry surround is configured as a simple, on/off piece for cleaning or a potentially disposable part. The entire instrument is also able to be easily cleaned and disinfected.
It is also an object to provide a simple and reliable test strip and meter for measuring the hemoglobin content of a blood sample.